package demo01;

/**
 * @author Gotcha
 * @date 2021/6/15
 * @describe
 */
//电脑类
public class Computer {

    public String readSD(SDCard sdCard) {
        if(sdCard == null) {
            throw new NullPointerException("没有找到SD卡");
        }
        return sdCard.readSD();
    }
}